Allow users (they have the capability to upload files) to upload html-files

Hello,

I have a problem with the wordpress upload-permissions. My aim is, that “contributers” are able to upload html-Files. I still have added the “upload_files”-capability to the contributers-role. That works. But contributers are not able to upload html-files. I don’t understand why.

Admins are able to upload html-files. Perhaps the unfiltered_upload-capability would solve the problem, but I don’t want to enable unfiltered_uploads for all contributers.

Is there a way to allow specific mime-types for specific user-roles?

Thanks a lot for your help!